The Underwear Effect
by ElizavetaHedervary
Summary: Eren is twenty-two years old and the titans have finally been defeated. Despite all he has been through, he learns that sometimes, you have to look on the bright side of things. Of course, things get a bit silly when a certain best friend mentions something he probably shouldn't have. Eremin fic! Mostly fluffy, but it has its serious points too!


**Author's Note: Wow, I had a lot of fun writing this! (Though I don't know how well it turned out!) It's basically a lot of Eremin nonsense and fluffiness! I'm so happy that you decided to read this and I would really appreciate any criticism!**

The stunning salty water continuously shifted, moving along to its own clock. Bare feet met soft, white sand, almost forgetting all of the bloodshed that had stained and tainted their owners. The day was almost over, as shown by the gradually declining through the silvery sky, and yet it felt like life had just begun. A crispy breeze ruffled sweatpants and button-down shirts, articles of clothing that seemed rather proper in comparison to the gear, the boots, and the straps that restrained their captives from relaxation and silence.

It was a miracle that they had survived, and they all knew it. The titans had finally been defeated. They won the war. But all good things come with a cost. The Scout Regiment had lost so many along the way. Some of the losses almost made the others give up. They had no will to live without their closest friends. Why bother? The titans wouldn't understand. They didn't have the brain capacity to feel remorse for their dead. Perhaps that was humanity's biggest flaw, the ability to feel sadness, or grief, or remorse. Or maybe it was their greatest advantage, the perception of feeling was the reason why they even bothered to fight. Eren knew he wouldn't have worked so long and hard to defeat the titans without the memory of his mother's death clinging to him like a soaked shirt.

It took a long time to defeat the titans. Eren had just turned twenty-two. He felt that maybe, just _maybe_ , he wasted what he was told would be the best years of his life. No. If it weren't for him, so many would be dead and the titans would have likely still terrorized the humans. It wasn't the olive-skinned boy that truly ended the war, but he believed strongly in the butterfly effect. The smallest of his own actions could have been the reason why Mikasa was able to slaughter what seemed to be the leader of the titans. The smallest of his own actions could have been the reason why she died shortly after. He would never forgive himself for that. Ever.

Not many in the Scout Regiment lived to be twenty-two. Eren knew that. He figured that he should feel lucky. If Mikasa hadn't done what she did, who knew how many people would be dead by now? Other loyal warriors, those that didn't deserve to die, those that embraced life for every second it was worth, hadn't made it either. Connie suffered a quick and _mostly_ painless death. His wires were caught in the strong grasp of a titan at the very last moment, sending him swinging headfirst into a crumbling wall. Jean also failed to be present at the end of the battle. No one truly knew what happened to him. Some said he had committed suicide, but Eren knew better. Jean was one of those people that never gave up, no matter what the circumstances were. Whatever happened to him, Jean was now with Marco _and_ Mikasa, and surely that would make him happy. Eren knew it wasn't his fault that Humanity's Strongest lost the fight. Levi was with Mikasa, helping her to defeat the "titan leader". After all, they were the two greatest warriors that humanity had ever seen. Both of them put a good fight, but Levi died first, making one simple, wrong move that sealed his fate. The butterfly affect happened again, didn't it? That one movement by Levi sent the titan lurching forward in an attempt to grab him, giving Mikasa enough time to make that one strike that ended it all. But she lost control and was crushed under the falling giant.

Eren could have saved her. That one moment of hesitancy, wasted, could have saved her. Maybe the ultimate sacrifice was necessary to spare the lives of thousands of people. That was all that was left after the titans were gone. Eren wiggled his toes, feeling the sand beneath his feet. If only there was something he could do to make Levi, Mikasa, Jean, and Connie stand alongside him.

But Eren had some people left. Hanji still remained, still as smart and eccentric as ever. However, there was something missing ever since Levi had died. Her eyes were a bit less bright, her posture was a bit less straight. Sasha has managed to make it through as well, but she almost didn't make it many times. Eren could tell that she missed everyone she lost. Annie managed to survive as well, all past emotion simply wiped off her face. Ymir and Christa still lived on. Despite all that had gone on around them, they managed to stay happy and keep an optimistic view on life. A few others made it too. Reiner and Bertolt, Erwin too.

One person stood beside Eren, feet in the sand, hair blowing in the wind. Armin had survived too. He might have started as a tiny fifteen-year-old, but he had certainly grown. Out of nowhere, Armin had become one of the best warriors. It almost annoyed Eren. Mikasa was such a great scout, easily better than him. Armin was practically a genius _and_ more talented and powerful than he was. It wasn't fair. All Eren had on his side was his ability to shift into a titan, and he had lost that ability once the last titan was slaughtered.

Eren had grown a lot over the years. He had certainly gotten taller, stronger, sturdier... Everything expected of an average man like him. Other than that, Eren hadn't changed much. He still had rough hands, a wild fire in his green eyes, and messy brown hair that still complemented his features just the same as when he was a teen. No matter how much Eren had grown, he was nothing compared to Armin. The blonde now stood a few inches taller than him, with a strong jaw and high cheekbones. It almost seemed impossible that he was the skinny boy he was before. Armin's bright blue eyes still seemed young and full of life. He still had an incredibly intelligent brain on his shoulders too. Even his golden hair had grown from its bowl cut to a stringy and loose ponytail that barely reached below his shoulders.

"I can't believe we made it," Armin whispered, staring out at the ocean that seemed to go on forever. Did it?

Eren nodded. "But did we? I mean, look who's dead. All of our loved ones, all of our friends..."

"Not all of them," the blonde replied. "Don't let someone else's fate turn your happy ending into a sad one. Mikasa wouldn't want that, Levi wouldn't either. Just be proud that you survive."

"My hesitance to save them was the flap of a butterfly's wings," Eren said. It surprised Armin, really, that someone like Eren would say something like this. "But the flap of a butterfly's wings can cause a hurricane on the other side of the world. Those deaths, they might not be mine, but they-they-" Tears were forming in green eyes as he said it.

Armin drew in a breath, watching the man beside him. "Eren, I don't think I've ever seen you cry before," he whispered. He put a hand on his shoulder, taking a gulp as the other flinched.

Eren sniffed, leaning into the sturdiness of the best friend that was once, _somehow_ , bullied for being different and weak. "I just can't believe they're all gone," he cried, though he kept his teeth gritted, trying to keep the idea that he was crying out of the conversation.

"Eren, just appreciate what they've given you. If Mikasa was still here, she'd tell you that. She'd say that what she did was her own choice and not yours. And I'm sure it's a choice she wouldn't regret if she could," Armin said.

The brunette slowly nodded. Armin began again, "Don't let the butterfly effect get to you. We still have each other to power through that hurricane."

Eren looked up at his friend, eyes still clouded over. "Armin, do you think that we could just be kids again? You know, have no worry in the world?"

"Well, the titans are gone. I think we both deserve a break," the man chuckled. Eren immediately grabbed the other's wrist in his hand and started bolting toward the sea. Armin grunted in surprise, nearly falling over as he was pulled forward. The blonde half-heartedly tried to pull away, yelling something like, "Eren, no! My clothes will get wet! And salty!"

Eren stopped in his tracks for a moment, looking behind him. "If you care _so_ much about that stupid shirt of yours, then take it off!" It was almost as if he wasn't crying just a minute before. He was back to the old Eren, and that was how Armin liked him.

"Yeah, but I don't really want to take my shirt off," Armin said.

"Then take your pants off and we won't go too deep," Eren replied.

Armin quickly shook his head, his eyes wide. "Uh, no can do Eren!"

Eren placed his hands on his hips. "And why would that be?"

"I may or may not be wearing underwear right now," Armin said sheepishly.

Eren sighed, looking down. Suddenly, in a low and playfully angry voice, he said, "Armin, care to explain why you aren't wearing underwear?"

"Uh, well, I dunno. I just kind of wanted to, I guess. What? Can't a man do what he wants?"

"Yeah, but _really,_ Armin? How often do you do this?"

"Well, I wasn't _expecting_ you to demand that I take off my clothes."

"Shut up, Armin, why are you making me sound like a chump?"

"I'm _not!_ Eren, do you even know what a chump is?"

"No, but I like the word. You know, let's just get in the water." Eren ran behind the other and started shoving him from behind. Armin dug his feet in the ground, and that was the end of that. He turned around and and smiled, raising a brow.

"Did you really think you could get off that easy, Eren?" he asked, his voice low. Before the other could say anything, he wrapped his arms around the other's waist and slung him around his shoulder.

Immediately, Eren complained, banging his fists on Armin's back. "You ass! Put me down!"

Armin laughed a bit as he walked into the water, no longer caring about how wet his pants would get. "What? Can't handle that you can be overpowered by someone without underwear on?"

"Armin! Oh my god! Stop talking about the underwear already!" Eren shouted, trying to wiggle free. "Or I will pants you!"

Armin bent forward, laughing so hard he almost fell over. Eren had begun laughing too, falling limp on the shoulder of his best friend. They were already knee deep in the water, and the sandy bottom steeply declined from there on. "Let me down now?" he asked.

"Not a chance," Armin replied. With that, he took a few more steps into the water and shoved the olive-skinned man off his shoulders, plunging into the water below. In a panic, he surged up, trying to paddle his way over to the blonde that stood about two feet away, laughing. "Eren. You do realize that you can stand, right?"

Eren looked up at him for a moment, as if he were crazy. Then, slowly, he brought himself to his feet, water dripping from his shaggy hair. "Yeah, I knew that," he said, quietly. Armin rolled his eyes, smirking. However, the tiny smile turned into a frown as the other man suddenly splashed him, sending water all over his front side.

"Eren! This is my nicest shirt!" he cried.

"I told you to take it off! Why did you wear it to the ocean anyway?" Eren asked.

"Same reason I decided to wear no underwear," he replied.

Eren rolled his eyes and glanced down at his shirt. "You'd better take it off now because I promise you it will be ruined if you keep it on," he threatened as he leaned down to wave his hands around in the water.

"The fact that you can get away with saying these things to me appalls me."

"You're my best friend. I do whatever I want."

"Yeah, okay, fine," Armin groaned and turned around. He waded through the water in the direction of the shore, quickly unbuttoning his white dress shirt and shrugging it off. He dropped the partially-wet fabric on the sand and turned to walk back into the water. Eren remained where he was the entire time, not daring to say a word. The other's chest was full of scars and bruises from battles gone by. Right. He couldn't heal himself during those times like Eren could. It was part of his titan ability. Armin didn't seem to care about that in particular as he walked closer.

Once he did get closer, Eren cleared his throat. "Kiss me," he said, quickly enough so Armin wouldn't hear it, but clearly enough so that he _would_.

"What?" he asked, raising a brow. "Why?"

"The same reason you aren't wearing underwear," he replied.

Armin took a deep breath, looking down. "Oh, okay."

"Please?" Eren asked, looking up at the other.

"Since when did you-"

Armin was cut off by Eren's firm hands on his shoulders, eyes narrowed and staring directly at him. "Since always."

"Oh. The truth is, same. I just... didn't know you wanted that too," Armin whispered.

"Well now you do, so do it," Eren said, barely budging.

Armin hesitated. "I don't know how."

Eren rolled his eyes. "You just go with it. Like how you just go without underwear."

" _Stop_ bringing that up."

"I'll never let you live this down."

"How are we friends exactly?"

"You know what? You're completely terrible at this," Eren said. He stoop on his toes so he was at equal height to the other male, his arms on the other's shoulders propelling him up. Quickly, but not lightly, he touched their lips. Armin tensed, unsure of what exactly to do. He blinked, feeling Eren's arms snake their way around his waist. He decided to copy his movements, but the moment of affection didn't last much longer. The brunette pulled back, smiling up at him. "See? Now you know how to do it. Kiss me."

"But we just- fine." He placed his hands on Eren's shoulders and planted a kiss on his lips. He tried to pull back, but Eren had found a way to grab his head and prevent him from moving. He deepened the kiss, suddenly feeling much more comfortable. Eren wouldn't let that happen, though. In a brief flash of light, Armin was on his butt, spitting water out of his mouth as the brunette laughed uncontrollably.

"What do you do that for?" Armin asked as he stood up and gave a playful punch to the other's shoulder.

"The same reason you aren't wearing underwear," Eren laughed.

 **Author's Note: Well, that was... something I guess. I'm terrible at writing anything romantic, but... I tried! I really hope you liked this! I might not be able to upload many stories while I'm away at school. We'll see. I'll probably have a bunch written and publish them all on my breaks. But, then again, anything could happen. I might be able to write more stories and upload them on a regular basis rather than all at once!**


End file.
